A 52-year-old man with poorly controlled hypertension presents with blurred vision. Fundoscopy reveals multiple fluffy white lesions in the superficial retina. The lesions marked **C** in the diagram show a characteristic pattern that radiates from the optic disc. What does this pattern reflect?

Explanation

## Why "Orientation of the retinal nerve fiber layer (RNFL)" is right Cotton wool spots (CWS) are focal infarctions of pre-capillary arterioles within the nerve fiber layer, causing accumulation of axoplasmic transport material (cytoid bodies — swollen ganglion cell axons). The characteristic pattern marked **C** that radiates from the optic disc directly reflects the anatomical orientation of the RNFL itself, as the nerve fibers converge toward the optic disc. This is a pathognomonic feature of CWS and helps distinguish them from other retinal lesions. (AK Khurana Ophthalmology 7e Ch 16) ## Why each distractor is wrong - **Distribution of retinal microaneurysms in diabetic retinopathy**: Microaneurysms are punctate red dots scattered throughout the retina without the radiating pattern seen in CWS. They do not follow RNFL orientation. - **Alignment of retinal arterioles and capillaries**: While CWS occur due to arteriolar ischemia, the lesions themselves align with nerve fiber layer anatomy, not vascular anatomy. Arterioles do not show the radial disc-centered pattern of CWS. - **Spread of retinal ischemia along the posterior ciliary arteries**: Posterior ciliary artery occlusion causes sector ischemia, not the characteristic radiating pattern of CWS seen in hypertensive or diabetic retinopathy. **High-Yield:** Cotton wool spots always radiate from the optic disc because they follow nerve fiber layer orientation — this is the key diagnostic clue distinguishing them from other retinal white lesions. [cite:AK Khurana Ophthalmology 7e Ch 16]